#include<iostream>
#include<cstdio>
#include<algorithm>
using namespace std;
const int N = 1010;
int n, m;
char a[N], b[N];
int f[N][N];
int main()
{
	scanf("%d %d", &n, &m);
	scanf("%s %s", a + 1, b + 1);
	for (int i = 1 ; i <= n ; ++i)
		for (int j = 1 ; j <= m ; ++j)
		{
			f[i][j] = max(f[i - 1][j], f[i][j - 1]);
			if (a[i] == b[j])
				f[i][j] = max(f[i][j], f[i - 1][j - 1] + 1);
		}
	printf("%d\n", f[n][m]);
	return 0;
}
